CSWDC operates under an Integrated Pollution Prevention and Control (IPPC) Permit issued by the Environment Agency. The Permit controls the storage, processing and thermal treatment of waste.
The permit sets our conditions for operation, including emission limits which have been set in line with the Waste Incineration Directive 2000/76/EC. The plant is operated such that it does not exceed these emission limits.
Emissions from the plant are continuously monitored and you can review our performance above. This information will be updated monthly.
Understanding Emissions
Information about the emissions, including how they are formed and how they are controlled can be found below:
Particulates (dust)
How are particulate emissions formed?
During the incineration of waste in the furnace particles of dust are released into the flue gas. This dust is combusted waste, soot, or dust that is too light to fall from the furnace as ash.
How are particulate emissions controlled?
The last part of the plants gas cleaning process is the bag filter housing. This contains banks of bag filters, which capture the particulates. This forms part of the Air Pollution Control Residues (APCR), which is transported off site for treatment and disposal.
There are many man-made sources of particulates, including road transport and industry. There are also natural sources, for example, volcanoes and dust storms.
Sulphur Dioxide (SO2)
How is Sulphur Dioxide formed?
Many waste streams and fossil fuels contain sulphur. Sulphur is present in the waste stream from batteries, plastics, waste oil, and gypsum-filled wallboard. It is released into the combustion gases during incineration and reacts with the oxygen in the air to produce sulphur dioxide.
How is Sulphur Dioxide controlled?
The flue gas cleaning process plant removes sulphur dioxide from the exhaust gases. The combustion gases enter the venturi reactor tower and hydrated lime is injected into the flue gas stream to remove any sulphur dioxide gas from the flue gas. This process converts the gaseous sulphur dioxide into a solid sulphate form, which is then captured by the bag filters, forming part of the APCR.
Sulphur dioxide is produced by burning coal and oil. Power stations and oil refineries release most of the sulphur dioxide in the air, but releases from domestic open fires can also affect local concentrations. Releases from its industrial uses are relatively small. Sulphur dioxide is also found naturally in the air at low concentrations from natural releases such as volcanoes and forest fires.
Oxides of Nitrogen (NOx)
How are oxides of nitrogen formed?
Oxides of nitrogen are mainly formed by two routes. Firstly, whenever anything is burnt in air, oxides of nitrogen are formed. This is because the air we breathe is made up of nitrogen (78%) and oxygen (21%) and these combine where heat from combustion is available – this is called thermal NOx. Secondly by nitrogen within the waste feed such as green waste. Nitrogen dioxide, and nitric oxide are both oxides of nitrogen and together referred to as NOx.
How are oxides of nitrogen emissions controlled?
Oxides of nitrogen are controlled through combustion control techniques and the use of Selective Non Catalytic Reduction (SNCR) with the injection of ammonium hydroxide, the ammonia reacts with the oxides of nitrogen to change it back into nitrogen (as found in air) plus water, the chemical reaction is NOX + NH3 → N2 + H2O.
Major man-made releases of nitrogen oxides are primarily from fuel combustion (including vehicles), biomass burning and some production processes. There are also minor natural sources such as lightning, natural fires and biological processes in soils and waters.
Carbon Monoxide (CO)
How is carbon monoxide formed?
Complete combustion is the basic purpose of the plant design; this converts the carbon in the waste into carbon dioxide in the presence of sufficient air. If sufficient air is not present then there is a formation of carbon monoxide.
How is carbon monoxide controlled?
The control of excess air within the process ensures complete combustion, and prevents the formation of carbon monoxide. The flue gas is monitored for carbon monoxide before the gas-cleaning phase, and this feeds back to the combustion air system. This feedback controls the amount of air introduced into the furnace.
The main man-made source of carbon monoxide is petrol vehicles which are not fitted with a catalytic converter. Small amounts are also released from the burning of fossil fuels in power stations and waste incinerators. Faulty domestic gas boilers, barbeques and domestic cookers are also sources and the gas is also found in tobacco smoke. Smaller amounts are also produced by natural processes, forest fires.
Hydrogen Chloride (HCl)
How is hydrogen chloride formed?
In the waste stream chlorine compounds can be found in the form of plastics (PVC), and inorganic salts (sodium chloride, household table salt). The chlorine is released into the combustion gases during incineration. The chlorine reacts with hydrogen in the combustion air to produce hydrogen chloride.
How is hydrogen chloride controlled?
The flue gas cleaning process plant removes hydrogen chloride from the exhaust gases. The combustion gases enter the venturi reactor tower and hydrated lime is injected into the flue gas stream to remove the acidic hydrogen chloride gas. This process converts the gaseous hydrogen chloride into a solid chloride form, which is then captured by the bag filters, forming part of the APCR.
The main source of hydrogen chloride releases are coal burning power stations, and cement and lime kilns.
Volatile Organic Compounds (VOCs)
How are volatile organic compounds formed?
Volatile organic compounds are commonly called VOCs, and can also be expressed as total organic carbon. The volatile organic compounds are present in the combustion gases from incomplete incineration of organic matter such as oil, and municipal waste.
How are Volatile Organic Compounds controlled?
VOCs are formed when there is incomplete combustion of organic material. Control and maintenance systems together with operating procedures are used to control emissions.
Paints, natural gas, petrol, road transport and industrial processes are the major sources of these compounds; however some are also produced by natural biological processes.
